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Unstable flight on customized FC40

Discussion in 'Phantom FC40 Help' started by DiceOfSeven, Mar 9, 2015.

  1. DiceOfSeven

    Joined:
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    Specs:
    - DJI FC40
    - DJI 2.4ghz controller installed
    - iLook+ camera & Gimbal (5.8ghz video feed back to black pearl monitor)
    - Dual battery setup

    To start I had a crash before this past winter so after the drone was repaired I didn't get to fly much however I noticed it was much less stable in flight. Thinking it was my nerves were shot from crashing it last time, thought the unstable nature was in my head. Today was nice and I took it out and got a bit more rough flying with it. So its not in my head.

    The drone will drift in GPS mode, I let go of the sticks, drifts two feet from where I let go then locks into position. Seems to favor going left when I'm looking at the camera (So its right).
    To give the gimbal a workout (or get it unstuck) I will do circles with the right stick, after this crash it wants to go down. Today I rotated the right stick and the DJI just about flipped over, it caught it self inches from the ground. I'm unsure what to make of it.

    Any idea? Bad GPS, Bad compass, Bad motors, or too heavy? (even though it was fine before the crash with the weight)

    I'm pretty much too scared to fly it since repairs take time and forever to get parts. Any ideas I can try? Maybe just put it all back to factory and see if it acts better?

    https://www.dropbox.com/s/m590f9s5ypuhdva/2015-03-09 18.42.42.jpg?dl=0
    https://www.dropbox.com/s/aap38zwt7epuji5/2015-03-09 18.43.09.jpg?dl=0
     
  2. Joesrevolution

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    Okay well for starters I'd recommend loosing the second battery and see how it works from there. It also looks to me that you are using the stock DJI props? If you have any extra weight other than a gimbal thrust boosted props are a must! Go for the official DJI 9450 props as these will give you roughly a 20% boost in power and similar extension in flight time. Also you shouldn't have issues with VRS which is when you descend too fast with a heavy bird causing your prop wash to cause problems. I assume after your crash you have done both the compass dance and an advanced imu calibration? If not plug it into the naza assistant and run an imu calibration on a flat surface away from metal ideally. The do your compass dance. See how that goes.

    As for it flipping over, I'm stuck. Maybe the extra batteries, maybe the imu is out. Just as a precaution though... you definitely weren't flying in manual mode? ;)

    Hopefully this helps!
     
  3. DiceOfSeven

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    I do have the 9450 real DJI props and I just threw the 8" on there for testing sake. I will try with one battery and see, I have not done the dance "and" the calibration in a while...however I do the dance every time before I fly as a precaution. I have manual mode off all together on my controller since with the monitor on my remote it's hard to flip those switches quickly.
     
  4. Joesrevolution

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    Yea well do both calibrations and then give the single battery set up along with the 9450 props a try and see how that goes.
     
  5. DiceOfSeven

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    So decided to dive into the phantom checking the GPS and everything making sure nothing was damaged. I noticed the board the IMU sits could be shifted about 1/16 of an inch so I ratcheted down the screws to keep it from moving....I'm waiting for the IMU to cool down but I am going to do both calibrations today, if I'm not stuck at work past dark I will do a test flight. I put the original legs on it and just one battery.
     
  6. J.James

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    That message that pops up saying the imu is too warm is a known error and bug that has no use or meaning at all and is to just be ignored and click ok.
     
  7. DiceOfSeven

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    Well screwing down the IMU has definitely improved the squirrliness. So running the tests, I also did a motor test, noticed 3 out of the 4 motors have begun a grinding sound...so my guess is the bearings are going out, *sigh* which could account for some drops in RPM if the bearing slows down the motor shaft. T-motors are on order...drones be expensive bros!

    Does not help the matter I'm in the process of building a larger form drone for longer air time and to carry a heavier 3 axis gimbal. The life of a hobbyist, am I right guys! lol
     
  8. IflyinWY

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    So, you tightened down the IMU board, did an advanced IMU calibration, did the compass dance and the flight was better, yes?

    And now the motors are grinding.
    Do you live in a high humidity climate or could dust have settled into the motors while it sat?

    That looks like one seriously heavy bird.
    What does it weigh?

    I've loaded mine like that and tried flying at 8,000 feet on a warm day with stock props... :lol: :lol: NO Dice baby.
    Less than a minute to drain the battery and very unstable.

    9450 props are the only way to go for me.

    Could you be doing your Compass Dance over buried power lines?
    I've done that and it's like giving it a shot of Whiskey.
     
  9. DiceOfSeven

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    Guess it could be over buried lines dint really think of that since most lines in my neighborhood are above ground...yes the flight is better the GPS still is not holding it still after I let go of the sticks I'm wondering if the gains need to be set higher. I have them at 110% to compensate for the bigger props. Thoughts? In GPS mode it should compensate to try and hold position after i let go of the sticks, but it drifts for a few feet, almost like its in a semi Atti mode.

    I do not have a an exact weight but its a lunker and flew great before I had the crash. I added the T-motors and it was a world of difference power wise for sure.